Scaler



Jlan. 29, 1957 w. l.. scHoENGARTH 2,779,085

SCALER 2 Sheets-SheefI l Filed Dec. 3l, 1954 `Iam. 29, 1957 w. L.SCHOENGARTH 2,779,085

SCALER Filed Dec. 31, 1954 2 Sheets-Sheet 2 Ti s--l @o 92 45e@ Se l 5c,

AT TOEN EYS United States Patent O SCALER Walter L. Schoengarth,Redding, Calif.

Application December 31, 1954, Serial No. 479,051

3 Claims. (Cl. 29-81) This invention relates to a tool for removingscale, slag, rust, carbon, paint and the like from metallic or othersurfaces.

Summarized briey, the invention is a hand held power tool in which,through the medium-of a motion translating linkage extending from anelectric motor, high speed reciprocation is imparted to a piston withina cylinder or pneumatic chamber, in a manner to impart a correspondinghigh speed movement to a plurality of plunger picks which, when directedagainst Ithe surface to be cleaned, rapidly remove scale, rust, othereiects of corrosion, paint, and the like. The picks are individuallyslidable in provided bores, so that, while all the picks are movedtoward and away from the work simultaneously, the lengths of theirstrokes will be governed by the conformation of the work surface. Thus,if some of .the picks encounter a particularly hard formation on thework while others strike relatively soft areas, the latter picks arepermitted to travel further inwardly of the work without adverse eiects,so as to facilitate the cleaning operation and so as, further, toparticularly adapt the device for use on uneven surfaces such as thoseoccurring at the location where an electric weld or the like has beenused to unite metals.

In accordance with the invention, the reciprocating motion of the picksresults from the creation, at the back ends of the same, of alternatingair pressure and vacuum conditions resulting from the reciprocation ofthe piston. Within the pneumatic chamber, between the picks and piston,a novelly formed valve assembly is so designed that an outlet valveopens when the picks are moved outwardly and an inlet valve opens whenthe picks are to be moved inwardly. The valve assembly is so designed asto hold the picks in their retracted positions, during the initial partof the pressure stroke of the piston, for a minute periodlof time, in amanner that causes a pressure to be built up against the picks with aresultant increase in the rapidity of their outstroke.

One important object is to provide a tool as stated which will bemanipulable with a high degree of facility, will be light in weight,durable, and efcient in removing diierent types of residues carried byboth even and uneven Work surfaces.

Another object is to provide a tool that will be safe in operation,compact, and capable of manufacture at relatively low cost consideringthe benefits to be obtained from use thereof.

Other objects Will appear from the following description, the claimsappended thereto, and from the annexed drawing, in which like referencecharacters designate like parts throughout the several views, andwherein:

Figure 1 is a top plan View of a tool formed in accordance with thepresent invention, in which a portion has been shown in longitudinalsection;

Figure 2 is an enlarged longitudinal sectional view 0n line 2--2 ofFigure l, the picks being shown in retracted position;

Figure 3 is a view on the same cutting plane as Figure 2 showing thehead end of the device applied to a pieceof work, the picks being shownin their extended position or outstroke; i

Figure 4 is a transverse sectional View on line v4--24 of Figure 2;

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Figure 5 is a transverse sectional view on line 5-5 of Figure 3;

Figure 6 is an exploded perspective View of the pick y control valveassembly; and

Figure 7 is an exploded perspective View of a vacuum relief valve.

The tool constituting the present invention includes a pistol griphandle 10 cast integrally with a cylindrical, hollow casing 12 formedintermediate its ends with a transverse partition 14 dividing the sameinto a motor compartment 16 and a driving linkage compartment 18. At oneend, the casing is integral with a reduced axial extension 20 ofcylindrical formation, providing a piston compartment or pneumaticchamber 22 communicating with compartment 18.

Fixedly mounted in the motor compartment 16 is a conventional electricmotor 24, to which power is supplied through a line cord 26. Mounted inthe handle is a trigger type switch 28 (Figure 4), where-by the motorcan be turned on or oil by the linger of a hand gripping the handle in anatural manner during use of the tool.

The shaft 30 of the motor extends axially of the casing and isjournalled in a bearing 32 provided in the partition 14. Shaft 30extends into the compartment 18, and is there secured to a beveled drivegear or pin 34 meshing with a bevel gear 36 carried by a stub shaftjournalled in a bearing 38 mounted on one side wall of the compartment18. A pitman 40 is connected to the gear 36 and is connected through themedium of a pin 42 tto a piston 44 having piston rings 46 in wipingengagement with the wall of the piston chamber 22. Thus, on operation ofthe motor the piston 44 is given high speed reciprocating movementbetween the respective positions shown in Figures 2 and 3.

On reciprocation of the piston, alternating pressure and vacuumconditions occur within chamber 22 to the left of the piston in Figure2, the piston creating high pressure within the chamber 22 when shiftedthrough its out stroke to the left in Figure 2 from the position thereofshown in this figure, and creating a vacuum when retracted toV itsFigure 2 position from its Figure 3 position.

Meansis provided to admit air into chamber 22 should the created Vacuumbe excessive. This means comprises a vacuum relief valve generallydesignated 48, the parts of which are shown in Figure 7. A restrictedbore 50 communicates at one end with the chamber 22, and at its otherend opens int-o a counterbore 52 on the bottom of which is seated a'concavo-convex spring washer 54 of the spider type. Connected by a rivetto the center of washer 54 is a valve disc 56 normally seating againstthe inner end of a nut 58. A second nut 60 cooperates with nut 58 inholding therebetween a dust screen 62, the nuts lbeing threaded into thecomplementarily tapped outer end portion of the counterbore, saidcounterbore being formed in a boss 64 integrally formed upon the outersurface of the extension 20 of the casing.

Normally, the spring washer 54 holds pin 56 firmly seated against nut58, and this will be true even when the piston moves through its vacuumstroke and creates a Vacuum condition within the pneumatic chamber '22.Should, however, the vacuum created be such -as to Similarly, occasionmay arise for permitting the escape of air from the. chamber 22, shouldthe piston, when v moving through its pressure stroke to its Figure' 3position, create a'pressure"condition beyond av predetermined;-

value within the chamber. To this end, there is provided a pressurereliefvalve shown in seated andv unseated positions in Figures 2 and 3respectively. A restricted bore 68 communicates at one end with'thechamber, and at its other end opens into a counterbore '70. A ballelement 72, is normally biased by spring 74 to a seated position closingthe bore 68, and holding the spring under proper tension are nuts 76between which is interposed a dust screen 78, said nuts being threadedinto the outer end portion of the counterbore. The counterbore is formedin an obliquely extended boss 66 integrally formed upon the outersurface of the extension Zii.

At its outer end, extension is counterbored as at 80, thus forming acircumferential internal shoulder at the base ofthe counterbore Si).vSeated against said shoulder is a plunger pick control valve assemblygenerally designated 82. In Figure 2,A the partsr of said assembly areshown in the position assumed thereby when the piston is at the end ofits vacuum stroke. In Figure 3 the parts are shown in their positionwhen the piston is at the end of its pressure stroke. The parts of thevalve assembly are shown per se in the exploded perspective view ofFigure 6.

Assembly S2 includes at its inner end, that is, the end thereof facedtoward the chamber 22, a concave-convex spring washer 84 of the spidertype, the ends of which bear against the marginal portion of a valvedisc 86. Disc 86 is normally forced by the pressure of the spring to aseated position against a larger valve disc 88. The disc 86 can beappropriately termed a suction valve disc, for the reason that whenunseated, it is unseated due to the creation of a vacuum condition inthe chamber 22, of a Value sufiicient to overcome the restraint ofspring 84 and thereby draw the disc 86 to the right to its Figure 2position. This causes the vacuum to be extended to the left in Figure 2beyond disc 86 into plunger pick bores to be described hereinafter forretracting the plunger picks. Disc SS, on the other hand, can beappropriately termed as a pressure valve disc. Disc 88 is normallyseated against the mentioned internal shoulder when there is a vacuumcondition within chamber 22. However, it is unseated and moves to theposition shown in Figure 3 when a pressure condition is created inchamber 22, so as to cause said pressure to be transmitted past the discS8 to the plunger pick bores.

The value -disc 88 is formed with a peripheral series of notches 96, themarginal area of the disc 88 in which the notches are formed normallyseating, in the retracted piston position, against the internal shoulderof extension 20. The notches are thus closed, and air under pressurecannot be ydirected therethrough under these circumstances.

Disc 88 4is also formed with an annular series of slot like portsA 92formed in the center portion of the disc 88, in communication with ashallow circular recess 91 ofA the disc.

The ports 92 are closed by the suction valve disc during the pressurestroke of the piston, the suction valve disc being urged into andiilling the shallow recess 91 under pressure from the spring washer 84under these operating conditions as shown in Figurev 3.

A second spring washer of the spider type designated at94.bears against.the disc 88, tendingto urge the same.

into engagement with. the4 internal shoulder of the casingl extension2i). At its periphery, the washer 94, is engaged against the marginalpart of a plunger pick head plate 96 of a diameter corresponding to thatof the counterbore Stb, and formed with a plurality of openings. 98 eachof which has a small notch 100 in communication therewith. A centeropening 98 is provided, together with an annular series4 of saidopeningsas shown, to particular. ac lvantage'V in. E igure. 6,.

A plunger;v pick housing, 102., of cylindrical, formation is .externallythreaded` atits. inner end,l to engage. in a complementarily threadedouter end portion of the counterbore 80. Exteriorly of the counterhore,the plunger pick housing is integrally formed with a collar 104 havingdiametrically opposite notches adapted to receive a Spanner wrench orsimilar tool to.l facilitate the connection of the housing 102 to thecasing extension 20. A jam nut 106 is threaded upon the housing 102,against the outer end of extension 20 to insure the firm retention ofthe housing 102 in its assigned position relative to the casingextension.

Formed in the housing 102 is a plurality of end to end, longitudinal,parallel plunger pick bores 108 registering With the openings 98 of theplate 96, said plate 96 abutting against the inner end, of the plungerpick housing 102 as shown in Figure 2. Slidably reciprocable:

within the pick bores 108 are plunger picks 110, these being ofelongated, cylindrical formation andzterminab ing at their outer,projecting ends in points 112. It will be understood, in this regard,that although conical points are shown on the picks, said points can beof any desired design and may be of the chisel type or, for thatVmatter, of any other type found suitable for accom'- plishing theparticular task with maximum eiciency. The plunger picks, in thisconnection, are interchangeable, so that the one tool can be providedwith a number of diiferent sets of picks, each having a different typeythe diameters of the pick bores, and by reason of this.

arrangement, there is created, as soon as the extension 114 of each pickmoves during the retraction of the pick into the associated opening 98,a bui-fer space or air cushion surrounding the back end of the pick anddesignated at 115 in Figure 2. The purpose of this is to reduce shocksthat might otherwise occur were the picks drawn back at high speed intoengagement with the head plate 96. The air buffer spaces, it will benoted, are completely closed when the extensions 114 move into openings9S, so as to cause air to be compressedV in said spaces to cushion theblow of the pick during its retraction, except for the provision of thesmall notches 100 communicating with the openings 98. These provide asmall relief port for each air buffer space which, at the conclusion ofthe retraction of the pick, permits the `delayed escape of air from theair buier space so as to promote the cushioning action.

The picks are also reduced to a slight extent in diameter at theirforward end portions as at 116, and formed in the main or large diameterportions of the picks are small, narrow, longitudinal slots 11S thatopen at one end upon the shoulder defined by the reduced diameterforward end portions 116.

The purpose of reducing the forward end portions of the picks indiameter relative to the diameter of the pick bores 1% is to provide anair buffer space not only at the back of the pick, but also at thefront, so that again, shocks are not transmitted, when the picks aremoved through their outstrokes, to the associated parts of the tool. Theslots 118, in this connection, move intocornmunication with radial bores(Figure 4) communieating the center pick bore with the pick bores of theannular series. The slots 113 communicate with the bores 120 immediatelyprior to movement of the picks to the full limit of their outwardstrokes, to provide an Communicating between the pick bores of theannular series and the outer surface of the pick housing are radialpassages 122, and extending about the pick housing, at the locationwhere the bores 122 open at their outer ends, is a cylindrically shapedlter screen 124. This is of a porous fiber, through which air can escapeat a limited rate, thus relieving the air butter spaces at the outerends of the picks. The filter screen is encased by a filter cup 126,having circumferentially spaced, longitudinally extending slots 128 andopenings 130 alternating with said slots (Figure l). The provision ofthe slots deines spring tongues on the cup, facilitating the applicationor removal of the same, and at the inner ends of the tongues, inwardlyturned lips 132 are formed, engaging in circumterentially extendinggrooves formed in the outer surface of the pick housing to hold the cupin place.

In use, the tool is disposed adjacent a piece of work W having, forexample, a deeply penetrating area of rust R varying in depth over itsentire area. To remove the rust, the tool is positioned as shown inFigure 3, and when the motor is turned on, the piston 44 willreciprocate at high speed. Alternating pressure and vacuum conditionsarc thus created in the chamber 22. When the piston moves through itspressure stroke from its Figure 2 to its Figure 3 position, air iscompressed in the chamber 22, and overcomes the restraint of the spring94 which ilattens somewhat as shown in Figure 3, causing the pressurevalve disc 88 to be unseated. The compressed air is thus forced throughthe peripheral series of notches 90, and impinges against the inner endsurfaces of the several plunger picks. The plunger picks are thus forcedinto their outstroke from their Figure 2 to the Figure 3 positions,against the area to be cleaned. It is important to note that some of thepicks may move further than other picks, depending upon the contour ofthe work surface and the resistance encountered by the picks when theystrike the work.

When the piston moves from its Figure 3 position to its Figure 2position in its vacuum stroke, a vacuum condition is created in chamber22, and at this time, valve disc 88 will seat as shown in Figure 2,while the restraint of spring 84 will be overcome causing the spring 84to be flattened, thus drawing the suction Valve disc 86 off its seat andpermitting the suction to be communicated through the ports 92 of valvedisc 88, to the plunger pick bore. As a result, vacuum is created ineach plunger pick bore, causing the pick thereof to be retracted to itsFigure 2 position.

The valve assembly 82 has a particularly valuable characteristic, inthat when the piston begins to move into its pressure stroke, spring 94does not yield immediately. Instead, for a relatively minute period oftime, the spring holds valve disc 88 in a seated position, causingpressure to be built up to the right of the valve disc in Figure 2.Further movement of the piston 44 through its pressure stroke causesspring 94 to' flex, so that the.

pressure is now transmitted to the plunger pick bores, causing the picksto be given a stroke of increased rapidity.

During the use of the tool, the same can be twisted or otherwisemanipulated, to bring the picks to bear against different areas duringthe high speed reciprocation of the same.

The tool is particularly adapted for cleaning surfaces having unevencontours, concavities, conveXities, or other conformations whichnormally present diiiculties when a multiplicity of power operatedcleaning elements are directed thereagainst in unison.

It is believed apparent that the invention is not necessarily confinedto the specific use or uses thereof described above, since it may beutilized for any purpose to which it may be suited. Nor is the inventionto be necessarily limited to the specic construction illustrated anddescribed, since such construction is only intended to be illustrativeof the principles, it being considered that the 6 invention comprehendsany minor change in construction that may be permitted within the scopeof the appended claims.

What is claimed is:

1. In a tool for cleaning residues, foreign deposits and the like from awork surface of the type comprising; a casing having a piston chamber, apiston reciprocating in the chamber to create alternating pressure andvacuum conditions therein and means for reciprocating the piston; a pickhousing carried by the casing and having a plurality of pick borescommunicating with said chamber; picks mounted in said bores forslidable reciprocation responsive to the creation of said alternatingconditions in the piston chamber; and a valve assembly mounted in saidchamber between the piston and pick bores and arranged to preventcommunication between the chamber and pick chambers for a predeterminedtime interval during the initial movement of the piston in its pressurecreating stroke, said assembly opening to communicate the chamber andbores during the remainder of the pressure stroke of the piston,

2. In a tool for cleaning residues, foreign deposits and the like from awork surface of the type comprising; a casing having a piston chamber, apiston reciprocating in the chamber to create alternating pressure andvacuum conditions therein and means for reciprocating the piston; a pickhousing carried by the casing and having a plurality of pick borescommunicating with said chamber; picks mounted in said bores forslidable reciprocation responsive to the creation of said alternatingconditions in the piston chamber; and a valve assembly interposedbetween the piston and the pick bores, said valve assembly including apressure valve disc unseating during the pressure receiving stroke ofthe piston to permit pressure to be transmitted from the chamber to thepick bores, and a vacuum valve disc unseating during the vacuum creatingstroke of the piston to cause the creation of a vacuum in the pick boresresponsive to the creation of a vacuum in said chamber.

3. In a tool for cleaning residues, foreign deposits and the like from awork surface of the type comprising; a casing having a piston chamber, apiston reciprocating in the chamber to create alternating pressure andvacuum conditions therein and means for reciprocating the piston; a pickhousing carried by the casing and having a plurality of pickborescommunicating with said charnber; picks mounted in said bores forslidable reciprocation responsive to the creation of said alternatingconditions in the piston chamber; and a valve assembly interposedbetween the piston and the pick bores, said valve assembly including apressure valve disc unseating during the pressure receiving stroke ofthe piston to permit pressure to be transmitted from the chamber to thepick bores, and a vacuum valve disc unseating during the vacuum creatingstroke of the piston to cause the creation of a vacuum in the pick boresresponsive to the creation of a vacuum in said chamber, the respectivevalve discs being spring loaded to resiliently and yieldably resistmovement to their unseated positions,

References Cited in the le of this patent UNITED STATES PATENTS 848,459Grant Mar. 26, 1907 974,267 Hennessy Nov. 1, 1910 1,024,395 Canty Apr.23, 1912 1,408,176 HDoubler Feb. 28, 1922 1,585,740 Saulia May 25, 19261,813,546 Schindler .Tuly 7, 1931 1,857,138 Campbell May 10, 19322,070,552 Ohlsson Feb. 9, 1937 2,091,408 Lewis Aug. 31, 1937 2,343,137Douglas Feb. 29, 1944 2,672,677 Arx Mar. 23, 1954

